1. Field
This disclosure relates to a speaker array apparatus capable of outputting sound beams from a speaker array having a plurality of speakers.
2. Description of the Related Art
Conventionally, a speaker array apparatus has distributed identical audio signals to a plurality of speakers that are arranged in a matrix form or in a line form and has applied a predetermined delay time to each of the distributed audio signals. Accordingly, a sound based on each of the audio signals simultaneously reaches a predetermined focal point in a listening space. As a result, the acoustic energy in the vicinity of the focal point is increased by in-phase addition. The speaker array apparatus, in this manner, produces a sound beam having a strong directivity in the focal direction.
As an invention related to such a speaker array apparatus, for example, an invention disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 is known. The speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 simultaneously outputs multichannel (for example, a center channel: Cch, a front left channel: Lch, a front right channel: Rch, a surround left channel: SLch, and a surround right channel: SRch) audio beams each having a different directivity.
In addition, the speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 reflects some of the multichannel audio beams on the wall surface of an installation space such as a room and then makes the audio beam for each channel reach a listening position from various directions. Thus, a listener at the listening position perceives an excellent surround effect.
A speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 (US 2008-0165979 A1), in order to reproduce a multichannel surround sound, requires the output direction of an audio beam of each of channels to be set correctly. Therefore, the speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711, while sweeping with a test sound beam, picks up a direct sound and a reflected sound of the test audio beam by a microphone that is arranged at the listening position. Then, the speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 obtains a relationship between an output angle of the test audio beam and a level of the picked-up audio signal. Thereafter, the speaker array apparatus specifies the output angle in which the level of the picked-up audio signal is at peak and determines the output angle of the audio beam of each channel based on the specified output angle.
In a multichannel surround sound, a mode adding a height channel has been proposed. The mode adds, to a horizontally directed sound field, a sound source of a height channel that reaches from the upper front side toward a listening position. Such a mode of adding the height channel enables a sound field according to a height or depth direction and thus can provide a higher level of the sound field.
The following considers a case in which the speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 outputs an audio beam of a height channel. Even in such a case, the output direction of the audio beam of the height channel is required to be set correctly. In view of the foregoing, the speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 may pick up a sound by a microphone that is arranged at a listening position while sweeping with a test audio beam in the vertical direction. Then, the speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 determines the output direction of the audio beam of the height channel based on the relationship between the output angle of the test audio beam and the level of the picked-up audio signal.
In a case in which the speaker array apparatus disclosed in Japanese Unexamined Patent Application Publication No. 2006-013711 sweeps with the test audio beam in the vertical direction, the microphone picks up a direct sound and a reflected sound of the test audio beam. As described above, the audio beam of the height channel is required to reach from the upper front side to the listening position. Therefore, the output direction of the audio beam of the height channel may preferably be set to an output angle of a test audio beam of which a reflected sound, reflected at a ceiling surface, has a peak of a signal level, among reflected sounds that the microphone has picked up. In another case in which the output direction of the audio beam of the height channel is set to an output angle corresponding to the direct sound of the test audio beam, a desired surround sound effect cannot be provided.